Surface mount technology (smt) pad design having contact strips with converging narrowing contact surfaces

ABSTRACT

An Information handling system (IHS) includes a circuit board assembly with surface mount technology (SMT) pad structure. Landing pad(s) attached to circuit board substrate have a mounting area that receive an SMT connector pin onto adjacent pair of differential contact strips plated to nonconductive surface and extending longitudinally in parallel alignment. A return current strip is longitudinally aligned, adjacent to the differential contact strips on a first lateral side. The return current strip is connected to a ground plane of the circuit board substrate. Converging narrowing of the adjacent differential contact strip increases separation from a distal end of the return current strip. The separation improves signal integrity by reducing fringe effects, increasing impedance, and quenching resonance. A surface mount device (SMD) has one or more connector pins that are attached to the one or more landing pads to conduct the high-speed communication signal.

BACKGROUND 1. Technical Field

The present disclosure relates in general to a surface mountedintegrated circuit in an information handling system (IHS), and moreparticularly to surface mount technology (SMT) connector pads for asurface mount device (SMD) in an IHS.

2. Description of the Related Art

As the value and use of information continue to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems (IHSs). AnIHS generally processes, compiles, stores, and/or communicatesinformation or data for business, personal, or other purposes, therebyallowing users to take advantage of the value of the information.Because technology and information handling needs and requirements varybetween different users or applications, IHSs may also vary regardingwhat information is handled, how the information is handled, how muchinformation is processed, stored, or communicated, and how quickly andefficiently the information may be processed, stored, or communicated.The variations in IHSs allow for IHSs to be general or configured for aspecific user or specific use such as financial transaction processing,airline reservations, enterprise data storage, or global communications.In addition, IHSs may include a variety of hardware and softwarecomponents that may be configured to process, store, and communicateinformation and may include one or more computer systems, data storagesystems, and networking systems.

Printed circuit boards (PCBs) in IHSs are increasingly using surfacemount technology (SMT) connectors for high speed signaling. SMTconnectors provide better impedance control than other integratedcircuit (IC) mounting technologies. Conventional connectors, such asplated through hole (PTH) or press-fit connectors, do not provide thesame signal integrity benefits as SMT connectors. With increasingcommunication speeds, additional considerations for signal integritybecome necessary even for SMT connectors.

BRIEF SUMMARY

In accordance with the teachings of the present disclosure, aninformation handling system (IHS) includes a circuit board assemblyhaving a circuit board substrate and a surface mount technology (SMT)pad structure. One or more landing pads of the SMT pad structure areattached to the circuit board substrate. Each landing pad has a mountingarea that is longitudinally sized to receive an SMT connector pin withina longitudinal mounting displacement tolerance value. Each landing padhas an adjacent pair of differential contact strips plated to anonconductive surface and longitudinally extending in parallelalignment. Each differential contact surface has converging narrowing ofeach strip at a distal end and has a proximal signal trace forconducting a high-speed communication signal to another functionalcomponent attached to the circuit board substrate. A return currentstrip is longitudinally aligned adjacent to the pair of differentialcontact strips on a first lateral side. The return current strip isconnected to a ground plane of the circuit board substrate. Theconverging narrowing of the adjacent differential contact stripincreases separation from a distal end of the return current strip. Theseparation improves signal integrity by reducing fringe effects,increasing impedance, and quenching resonance. A surface mount device(SMD) has one or more connector pins that correspond to and are attachedto the one or more landing pads to conduct the high-speed communicationsignal.

In accordance with embodiments of the present disclosure, a circuitboard assembly of an IHS includes a SMT pad structure. One or morelanding pads of the circuit board assembly are attached to the circuitboard substrate. Each landing pad has a mounting area that islongitudinally sized to receive an SMT connector pin within alongitudinal mounting displacement tolerance value. Each landing pad hasan adjacent pair of differential contact strips plated to anonconductive surface and longitudinally extending in parallelalignment. Each differential contact surface has converging narrowing ofeach strip at a distal end. Each differential contact surface has aproximal signal trace for conducting a high-speed communication signalto another functional component attached to the circuit board substrate.The circuit board assembly has a return current strip that islongitudinally aligned adjacent to the pair of differential contactstrips on a first lateral side. The return current strip is connected toa ground plane of the circuit board substrate. The converging narrowingof the adjacent differential contact strip increases separation from adistal end of the return current strip. The separation improves signalintegrity by reducing fringe effects, increasing impedance, andquenching resonance. The circuit board assembly includes a SMD havingone or more connector pins that correspond to and are attached to theone or more landing pads to conduct the high-speed communication signal.

According to illustrative embodiments of the present disclosure, amethod includes attaching an adjacent pair of differential contactstrips to a nonconductive surface of respective landing pads of a SMTpad structure of a circuit board substrate. The pair of differentialcontact strips have converging narrowing at a respective distal end.Each differential contact strip has a proximal signal trace forconducting a high-speed communication signal to another functionalcomponent attached to a circuit board substrate. The method includesattaching a return current strip that is longitudinally aligned adjacentto the pair of differential contact strips on a first lateral side. Thereturn current strip is connected to a ground plane of the circuit boardsubstrate. The converging narrowing of the adjacent differential contactstrip increases separation from a distal end of the return currentstrip. The separation improves signal integrity by reducing fringeeffects, increasing impedance, and quenching resonance. The methodincludes attaching a SMD having one or more connector pins thatcorrespond to and are attached to the one or more landing pads toconduct the high-speed communication signal and to form a circuit boardassembly of an information handling system.

The above presents a general summary of several aspects of thedisclosure in order to provide a basic understanding of at least someaspects of the disclosure. The above summary contains simplifications,generalizations and omissions of detail and is not intended as acomprehensive description of the claimed subject matter but, rather, isintended to provide a brief overview of some of the functionalityassociated therewith. The summary is not intended to delineate the scopeof the claims, and the summary merely presents some concepts of thedisclosure in a general form as a prelude to the more detaileddescription that follows. Other systems, methods, functionality,features and advantages of the claimed subject matter will be or willbecome apparent to one with skill in the art upon examination of thefollowing figures and detailed written description.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the illustrative embodiments can be read inconjunction with the accompanying figures. It will be appreciated thatfor simplicity and clarity of illustration, elements illustrated in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements are exaggerated relative to otherelements. Embodiments incorporating teachings of the present disclosureare shown and described with respect to the figures presented herein, inwhich:

FIG. 1 illustrates a block diagram representation of an exampleinformation handling system (IHS) having a circuit board assembly thatincorporates surface mount technology (SMT) landing pads, according toone or more embodiments;

FIG. 2 illustrates a top detail view of three versions of SMTdifferential contact strips for SMT landing pads, according to one ormore embodiments;

FIG. 3 illustrates a top detail view of connection pins of a surfacemount device (SMD) attached to two of the three versions of SMTdifferential contact strips, according to one or more embodiments;

FIG. 4 illustrates a time domain graphical plot of impedance profiles ofa generally-known 4 mm differential contact strip (“baseline connector”)and a straight tapered differential contact strip, according to one ormore embodiments;

FIG. 5 illustrates a time domain graphical plot of impedance profiles ofthe straight tapered differential contact strip and a curved tapereddifferential contact strip, according to one or more embodiments;

FIG. 6 illustrates a frequency domain graphical plot of insertion lossof the baseline connector, the straight tapered differential contactstrip, the curved tapered differential contact strip and a controlshortened differential contact strip, according to one or moreembodiments;

FIG. 7 illustrates a frequency domain graphical plot of return loss ofthe baseline connector, the straight tapered differential contact strip,the curved tapered differential contact strip and the control shorteneddifferential contact strip, according to one or more embodiments;

FIG. 8A illustrates a top view of a generally-known 4 mm rectangularpad;

FIG. 8B illustrates a top view of simulated electric fields (E-Fields)generated by the generally-known 4 mm rectangular pad;

FIG. 8C illustrates a top view of a graphical depiction of magneticfields (H-Fields) generated by the generally-known 4 mm rectangular pad;

FIG. 9A illustrates a top view of the straight tapered pad, according toone or more embodiments;

FIG. 9B illustrates a top view of a graphical depiction of E-Fieldsgenerated by the straight tapered pad, according to one or moreembodiments;

FIG. 9C illustrates a top view of a graphical depiction of H-Fieldsgenerated by the straight tapered pad, according to one or moreembodiments;

FIG. 10A illustrates a top view of the curved tapered pad, according toone or more embodiments;

FIG. 10B illustrates a top view of a graphical depiction of E-Fieldsgenerated by the curved tapered pad, according to one or moreembodiments;

FIG. 10C illustrates a top view of a graphical depiction of H-Fieldsgenerated by the curved tapered pad, according to one or moreembodiments; and

FIG. 11 illustrates a flow diagram of a method of making a circuit boardassembly of an IHS having SMT landing pads, according to one or moreembodiments.

DETAILED DESCRIPTION

According to the present disclosure, an information handling system(IHS) includes a circuit board assembly with surface mount technology(SMT) pad structure that has improved signal integrity for nextgeneration communication signal speeds. Landing pad(s) attached tocircuit board substrate have a mounting area that receive an SMTconnector pin onto an adjacent pair of differential contact stripsplated to nonconductive surface and longitudinally extending in parallelalignment. Return current strip is longitudinally aligned adjacent tothe pair of differential contact strips on a first lateral side. Thereturn current strip is connected to a ground plane of the circuit boardsubstrate. Converging narrowing of the adjacent differential contactstrip increases separation from a distal end of the return currentstrip. Separation improves signal integrity by reducing fringe effects,increasing impedance, and quenching resonance. A surface mount device(SMD) has one or more connector pins that correspond to and are attachedto the one or more landing pads to conduct the high-speed communicationsignal.

The present innovation recognizes that current SMT landing paddimensions can create problems at next generation speeds of greater than12 Gbps. The present innovation further recognizes that providingsufficient size for mechanical registration and stability of SMTconnector also provides more coupling area. With more capacitivecoupling, crosstalk between channels increases, insertion lossincreases, and impedance is lowered. The current return path carries asignificant level of current causing resonances. The present innovationrecognizes that a distal, unused portion of the landing pad acts as amicrostrip monopole at these frequencies and creates unsatisfactorysignal integrity for next generation communication signals. The presentinnovation addresses these deficiencies with a differential contactstrip design with satisfactory size for mechanical registration withreduced coupling with the return current strip for improved signalintegrity.

References within the specification to “one embodiment,” “anembodiment,” “embodiments”, or “one or more embodiments” are intended toindicate that a particular feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present disclosure. The appearance of such phrases invarious places within the specification are not necessarily allreferring to the same embodiment, nor are separate or alternativeembodiments mutually exclusive of other embodiments. Further, variousfeatures are described which may be exhibited by some embodiments andnot by others. Similarly, various requirements are described which maybe requirements for some embodiments but not other embodiments.

It is understood that the use of specific component, device and/orparameter names and/or corresponding acronyms thereof, such as those ofthe executing utility, logic, and/or firmware described herein, are forexample only and not meant to imply any limitations on the describedembodiments. The embodiments may thus be described with differentnomenclature and/or terminology utilized to describe the components,devices, parameters, methods and/or functions herein, withoutlimitation. References to any specific protocol or proprietary name indescribing one or more elements, features or concepts of the embodimentsare provided solely as examples of one implementation, and suchreferences do not limit the extension of the claimed embodiments toembodiments in which different element, feature, protocol, or conceptnames are utilized. Thus, each term utilized herein is to be given itsbroadest interpretation given the context in which that terms isutilized.

FIG. 1 illustrates a block diagram representation of an exampleinformation handling system (IHS) 100 having a circuit board assembly102 that incorporates SMT landing pads 104 for mounting of one or moreSMDs 106. The circuit board assembly 102 is economically assembled by anautomated manufacturing system 108 with placement tolerances on acircuit board substrate 110 of the circuit board assembly 102. Featuresof the SMT landing pads 104 provide satisfactory signal integrity fornext generation communication signals that pass through the SMT landingpads 104, even providing the placement tolerances.

Within the general context of IHSs, the IHS 100 may include anyinstrumentality or aggregate of instrumentalities operable to compute,classify, process, transmit, receive, retrieve, originate, switch,store, display, manifest, detect, record, reproduce, handle, or utilizeany form of information, intelligence, or data for business, scientific,control, entertainment, or other purposes. For example, an IHS may be apersonal computer, a PDA, a consumer electronic device, a networkstorage device, or any other suitable device and may vary in size,shape, performance, functionality, and price. The information handlingsystem may include random access memory (RAM), one or more processingresources such as a central processing unit (CPU) or hardware orsoftware control logic, ROM, and/or other types of nonvolatile memory.Additional components of the information handling system may include oneor more disk drives, one or more network ports for communicating withexternal devices as well as various input and output (I/O) devices, suchas a keyboard, a mouse, and a video display. The information handlingsystem may also include one or more buses operable to transmitcommunications between the various hardware components.

Referring again to FIG. 1, IHS 100 has a processor subsystem 112 that iscoupled to system memory 114 via system interconnect 116. Systeminterconnect 116 can be interchangeably referred to as a system bus, inone or more embodiments. Also coupled to system interconnect 116 isnon-volatile storage (e.g., a non-volatile random access memory (NVRAM)storage 118, within which can be stored one or more software and/orfirmware modules and one or more sets of data that can be utilizedduring operations of management IHS 100. These one or more softwareand/or firmware modules can be loaded into system memory 114 duringoperation of management IHS 100. Specifically, in one embodiment, systemmemory 114 can include therein a plurality of such modules, includingone or more of application(s) 120, operating system (OS) 122, basicinput/output system (BIOS) or Uniform Extensible Firmware Interface(UEFI) 124, and firmware (F/W) 126. These software and/or firmwaremodules have varying functionality when their corresponding program codeis executed by processor subsystem 112 or secondary processing deviceswithin management IHS 100. For example, application(s) 120 may include aword processing application, a presentation application, and amanagement station application, among other applications.

IHS 100 further includes one or more input/output (I/O) controllers 130which support connection by and processing of signals from one or moreconnected input device/s 132, such as a keyboard, mouse, touch screen,or microphone. I/O controllers 130 also support connection to andforwarding of output signals to one or more connected output devices134, such as a monitor or display device or audio speaker(s).Additionally, in one or more embodiments, one or more device interfaces136, such as an optical reader, a USB, a card reader, Personal ComputerMemory Card International Association (PCMCIA) slot, and/or ahigh-definition multimedia interface (HDMI), can be associated with IHS100. Device interface(s) 136 can be utilized to enable data to be readfrom or stored to corresponding removable storage device(s) 138, such asa compact disk (CD), digital video disk (DVD), flash drive, or flashmemory card. In one or more embodiments, device interface(s) 136 canfurther include general purpose I/O interfaces such as inter-integratedcircuit (I²C), system management bus (SMB), and peripheral componentinterconnect (PCI) buses.

IHS 100 comprises a network interface controller (NIC) 140. NIC 140enables IHS 100 and/or components within IHS 100 to communicate and/orinterface with other devices, services, and components that are locatedexternal to IHS 100. These devices, services, and components caninterface with IHS 100 via an external network, such as example network142, using one or more communication protocols that include transportcontrol protocol/internet protocol (TCP/IP) and network block device(NBD) protocol. Network 142 can be a local area network, wide areanetwork, personal area network, and the like, and the connection toand/or between network and IHS 100 can be wired, wireless, or acombination thereof. For purposes of discussion, network 142 isindicated as a single collective component for simplicity. However, itshould be appreciated that network 142 can comprise one or more directconnections to other devices as well as a more complex set ofinterconnections as can exist within a wide area network, such as theInternet.

The SMT landing pads 104 are formed on an exposed surface of the circuitboard assembly 102 by etching from copper sheets laminated onto anon-conductive substrate. The SMT landing pads 104 have sufficient sizefor mechanical registration and stability to enable economicalmanufacture and assembly of surface mode devices (SMDs) onto the circuitboard assembly 102 using automated processes. As illustrated within thefigure, the automated manufacturing system 108 can be an IHS 100 such asincluding a processor 144 that executes an assembly utility 146 underremote management via a network interface 148 that communicates withnetwork 142. A robotic end effector 150 can place connector pins 152 ofthe surface mount device (SMD) 106 onto the SMT landing pads 104 forattachment, such as by soldering. The SMT landing pads 104 includereturn current strips 154 to one or both lateral sides of a pair ofdifferential contact strips 156, 158 that are electrically connected aspositive and negative values to a high communication speed functionalcomponent 160 of the IHS 100.

FIG. 2 illustrates SMT landing pads 200, which includes three versionsof landing pads 200 a, 200 b, 200 c that respectively includedifferential pairs of tapered, rounded and shortened contact strips 202a-202 b, 204 a-204 b, 206 a-206 b respectively. Each of the landing pads200 a, 200 b, 200 c are shown to improve signal integrity at nextgeneration speeds over a generally-known baseline contact strips (shownin phantom) 208 a-208 b. The width of the baseline contact strips areselected to make suitable contact area with the MSD 106 (FIG. 1). Thelength is selected based on the placement tolerance of an automatedmanufacturing system 108 (FIG. 1). In the presented example, theconventional baseline contact strips are two parallel and rectangularcontact strips of 4 mm in longitudinal length and 0.66 mm laterally wideeach for a contact area of 2.64 mm². Proximally attached traces 210communicate with other functional components 160 (FIG. 1). The 4 mm oflongitudinal length provides adequate placement tolerance for aconnector pin 152 (FIG. 1). In particular, the 4 mm longitudinal lengthprovides an economical tolerance for automated assembly of an SMD havingcontact area of each connector pin of about 0.5 to 0.8 mm inlongitudinal length. However, generally a distal portion of the Baselinecontact strips 208 a-208 b extend out as monopole stubs that can createelectromagnetic transmission problems at high communication speeds, suchas speeds exceeding 12 gigabytes per second (Gbps). Current can bereceived by a flanking pair of return current strips 212 due to fringeeffects and resonance. Generally, the return current strips 212 providea benefit since one or the other of contact strips 208 a-208 b can havean imbalanced amount of current due to differences in propagationeffects on both sides of the current flow. However, in this instance,creation of a resonance on the unused distal portion of the contactstrips 208 a-208 b lowers the impedance and degrades insertion andreturn losses.

The shortened contact strips 206 a-206 b provide a control caseillustrating avoidance of a stub portion by shortening longitudinallength to 2.8 mm. However, the shortened contact strips 206 a-206 brequire a more complex and costly approach to automated assembly inorder to place the connector pins 152 (FIG. 1) on this reducedlongitudinal length. By contrast, the tapered and rounded differentialcontact strips contact strips 202 a-202 b, 204 a-204 b of the presentdisclosure maintain a 4 mm longitudinal length for economical assembly,but also incorporate a converging, narrowing of a distal portion tocreate separation from the flanking return current strips 212 on eachlateral side. The amount of contact area removed is 14% and 8%respectively. The resulting reduction in fringe effect and correspondingimprovement in signal integrity is far greater than this modest removalof contact area would suggest. The increased impedance quenches anyresonance by the converging, narrowing distal stubs. In one or moreembodiments, each return current strip 212 is connected by a platedthrough-hole or via to a ground plane of the circuit board assembly 102(FIG. 1) and is not part of a landing pad.

In exemplary embodiments, the pair of tapered differential contactstrips 202 a-202 b each have a proximal rectangular portion 216 of 2.8mm in longitudinal length and 0.66 mm in lateral width that transitionsto a distal right triangle portion 218 also of initial width 0.66 mm.The distal right triangle portion 218 has internally opposed sides of1.2 mm in longitudinal length with a linear tapered side toward aclosest return current strip 212. The pair of rounded differentialcontact strips 204 a-204 b each have a proximal rectangular portion 220of 2.8 mm in longitudinal length and 0.66 mm in lateral width thattransitions to a distal curved blade portion 222 also of initial width0.66 mm. The distal curved blade portion 222 has internally opposedsides of 1.2 mm in longitudinal length with a rounded side toward aclosest return current strip 212.

FIG. 3 illustrates a circuit board assembly 300 formed by SMD 302 havingconnector pins 304 a-304 g mounted respectively to SMT landing pads 306a-306 g. For clarity, details of the contact strips for low speedcommunication signals and differential high speed communication signalsare omitted as well as omitting return current paths. Each of landingpads 306 a-306 g provides economical mechanical registration for theconnector pins 304 a-304 g. The present innovation can avoid or mitigatean aggravating factor of communication speeds going beyond 12 Gbps to 16Gbps and 24 Gbps. In addition, the SMT landing pads 306 a-306 g do notcompromise the mechanical sturdiness of the connector by maintaining therequired pad height for mechanical reliability. The length of thetapered section can be controlled and based on modeling and simulationresults. A range from 0.5 to 0.3 times of the total pad length isrecommended. FIG. 3 illustrates a scenario when mechanical registrationtolerance results in placement of the contact pin contact 308 creating arelatively large distal, unused portion 310 of each landing pads 306a-306 g and a relatively short proximal, used portion 312.

FIG. 4 illustrates a graphical plot 400 of the generally-known baselineSMT connector of a pin soldered to a baseline SMT pad compared againstthe tapered landing pad. The tapering reduces the fringe effect and alsoimproves an impedance profile. Additionally, as shown in FIG. 3, theedges of the landing pads can be been made spherical for reducing chargedistribution. Time domain analysis shows there is no charge on thereturn current pads and this will result in quenching the resonance. Asillustrated in FIG. 4, impedance is improved by 10-15 Ohms with thetapered design.

FIG. 5 illustrates a graphical plot 500 of the straight tapered contactstrip compared against the curved tapered contact strip. Although theamount of contact surface removed differs respectively from 14° to 8°,the curved and straight tapered contact surfaces have similar impedanceprofiles.

FIG. 6 illustrates a frequency domain graphical plot 500 of insertionloss of the baseline connector, the straight tapered differentialcontact strip, the curved tapered differential contact strip and acontrol shortened differential contact strip, according to one or moreembodiments. FIG. 7 illustrates a frequency domain graphical plot 700 ofreturn loss of the baseline connector, the tapered differential contactstrip, and the control shortened differential contact strip, accordingto one or more embodiments. The tapered and rounded contact stripsperform comparable to the expensive shortened contact strip approach.The present innovation thus is shown to provide a number of desirableattributes: (i) mechanical stability is maintained while ensuringsuperior electrical performance for next generation speeds; (ii) a costeffective solution reduces the electrical field density and results insuperior electrical performance; (iii) decreasing capacitive effect isintroduced by landing pads and thereby the impedance is improved; (iv)better return loss and insertion loss are achieved; and (v) crosstalk ismitigated because of the differential property maintained at the landingpad edges.

FIG. 8A illustrates a generally-known 4 mm rectangular pad 800. FIG. 8Billustrates a graphical depiction 810 of electric fields (E-Fields)generated by the generally-known 4 mm rectangular pad 800. FIG. 8Cillustrates a graphical depiction 820 of magnetic fields (H-Fields)generated by the generally-known 4 mm rectangular pad 800. Significantfringe effects and charge accumulation is evident that corresponds tothe reduction in impedance.

FIG. 9A illustrates a straight tapered pad 900. FIG. 9B illustrates agraphical depiction 910 of E-Fields generated by the straight taperedpad 900. FIG. 9C illustrates a graphical depiction 920 of simulatedH-Fields generated by the straight tapered pad 900. Fringe effects aregreatly reduced corresponding to the increase in impedance.

FIG. 10A illustrates a curved tapered pad 1000. FIG. 10B illustrates agraphical depiction 1010 of E-Fields generated by the curved tapered pad1000. FIG. 10C illustrates a graphical depiction 1020 of simulatedH-Fields generated by the curved tapered pad 1000. Fringe effects aregreatly reduced corresponding to the increase in impedance. In additionthe greater length of the curved surface than a straight surface reducescharge accumulation.

FIG. 11 illustrates a flowchart of an exemplary methods 1100 by which anautomated manufacturing system 108 (FIG. 1) and/or an IHS 100 (FIG. 1)performs different aspects of the processes that enable the one or moreembodiments of the disclosure. Generally, method 1100 representscomputer-implemented methods. The description of method 1100 is providedwith general reference to the specific components illustrated withinFIG. 1.

Specifically, FIG. 11 illustrates a method 1100 for making a circuitboard assembly with SMT landing pads capable of next generationcommunication signal speeds with sufficient signal integrity. In one ormore embodiments, method 1100 begins with attaching, by an automatedmanufacturing system, an adjacent pair of differential contact strips toa nonconductive surface of respective landing pads of a surface mounttechnology (SMT) pad structure of a circuit board substrate (block1102). Method 1100 includes forming converging narrowing distal ends ofthe pair of differential contact strips (block 1104). Method 1100includes attaching a proximal signal trace to each differential contactstrip for conducting a high-speed communication signal to anotherfunctional component attached to a circuit board substrate (block 1106).Method 1100 includes attaching a first return current strip that islongitudinally aligned adjacent to the pair of differential contactstrips on a first lateral side (block 1108). Method 1100 includesconnecting the first return current strip to a ground plane of thecircuit board substrate (block 1110). Method 1100 includes attaching asecond return current strip that is longitudinally aligned adjacent tothe pair of differential contact strips on a second lateral side (block1112). Method 1100 includes connecting the second return current stripto the ground plane of the circuit board substrate (block 1114). Theconverging narrowing of the adjacent differential contact stripincreases separation from a distal end of the return current strip. Theseparation improves signal integrity by reducing fringe effects,increasing impedance, and quenching resonance. Method 1100 includesattaching a surface mount device (SMD) having one or more connector pinsthat correspond to and are attached to the one or more landing pads toconduct the high-speed communication signal (block 1116). Method 1100forms a circuit board assembly of an information handling system.

In one or more embodiments, the converging narrowing of each strip is atapered end. In one or more embodiments, the converging narrowing ofeach strip is a rounded end. The longitudinal length of the convergingnarrowing portion of each strip of the pair of differential contactstrips can be within a range of 30-50% of a total longitudinal length ofthe respective landing pad.

In the above described flow chart of FIG. 11, one or more of the methodsmay be embodied in an automated manufacturing controller that performs aseries of functional processes. In some implementations, certain stepsof the methods are combined, performed simultaneously or in a differentorder, or perhaps omitted, without deviating from the scope of thedisclosure. Thus, while the method blocks are described and illustratedin a particular sequence, use of a specific sequence of functionalprocesses represented by the blocks is not meant to imply anylimitations on the disclosure. Changes may be made with regards to thesequence of processes without departing from the scope of the presentdisclosure. Use of a particular sequence is therefore, not to be takenin a limiting sense, and the scope of the present disclosure is definedonly by the appended claims.

One or more of the embodiments of the disclosure described can beimplemented, at least in part, using a software-controlled programmableprocessing device, such as a microprocessor, digital signal processor orother processing device, data processing apparatus or system. Thus, itis appreciated that a computer program for configuring a programmabledevice, apparatus or system to implement the foregoing described methodsis envisaged as an aspect of the present disclosure. The computerprogram may be embodied as source code or undergo compilation forimplementation on a processing device, apparatus, or system. Suitably,the computer program is stored on a carrier device in machine or devicereadable form, for example in solid-state memory, magnetic memory suchas disk or tape, optically or magneto-optically readable memory such ascompact disk or digital versatile disk, flash memory, etc. Theprocessing device, apparatus or system utilizes the program or a partthereof to configure the processing device, apparatus, or system foroperation.

While the disclosure has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the disclosure. Inaddition, many modifications may be made to adapt a particular system,device or component thereof to the teachings of the disclosure withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the disclosure not be limited to the particular embodimentsdisclosed for carrying out this disclosure, but that the disclosure willinclude all embodiments falling within the scope of the appended claims.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The description of the present disclosure has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the disclosure in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope of the disclosure. Thedescribed embodiments were chosen and described in order to best explainthe principles of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

1. A circuit board assembly of an information handling system (IHS), thecircuit board assembly comprising: a circuit board substrate having anonconductive surface; a surface mount technology (SMT) pad structurecomprising: one or more landing pads attached to the circuit boardsubstrate and having a mounting area that is longitudinally sized toreceive an SMT connector pin of a surface mount device (SMD) within aplacement tolerance, each landing pad comprising: an adjacent pair ofdifferential contact strips plated to the nonconductive surface andlongitudinally extending in parallel alignment, each differentialcontact strip having converging narrowing of each strip at a distal endand having a proximal signal trace for conducting a high-speedcommunication signal to another functional component attached to thecircuit board substrate; and a return current strip that islongitudinally aligned adjacent to the pair of differential contactstrips and connected to a ground plane of the circuit board substrate,the converging narrowing of the adjacent differential contact stripincreasing separation from a distal end of the return current strip, theseparation improving signal integrity by reducing fringe effects,increasing impedance, and quenching resonance; and a surface mountdevice (SMD) having one or more connector pins that correspond to andare attached to the one or more landing pads to conduct high-speedcommunication signals.
 2. The circuit board assembly of claim 1, whereinthe converging narrowing of each strip comprises a tapered end.
 3. Thecircuit board assembly of claim 1, wherein the converging narrowing ofeach strip comprises a rounded end.
 4. The circuit board assembly ofclaim 1, wherein a longitudinal length of a converging narrowing portionof each strip of the pair of differential contact strips is within arange of 30-50% of a total longitudinal length of the respective landingpad.
 5. The circuit board assembly of claim 1, further comprising a nextreturn current strip that is longitudinally aligned adjacent to the pairof differential contact strips, the next return current strip connectedto the ground plane of the circuit board substrate.
 6. The circuit boardassembly of claim 1, wherein the SMT landing pad is formed by: attachinga metallic layer onto a surface of the circuit board substrate; etchingthe metallic layer to leave the adjacent pair of differential contactstrips; attaching a return current strip; and attaching a raisedrectangular ridge around the adjacent pair of differential contactstrips to form the landing pad to guide the SMT connector pin of theSMD.
 7. An information handling system (IHS) comprising: a circuit boardassembly comprising: a circuit board substrate having a nonconductivesurface; a surface mount technology (SMT) pad structure comprising: oneor more landing pads attached to the circuit board substrate and havinga mounting area that is longitudinally sized to receive an SMT connectorpin of an surface mount device (SMD) within a longitudinal mountingdisplacement tolerance value, each landing pad comprising: an adjacentpair of differential contact strips plated to the nonconductive surfaceand longitudinally extending in parallel alignment, each differentialcontact surface having converging narrowing of each strip at a distalend and having a proximal signal trace for conducting a high-speedcommunication signal to another functional component attached to thecircuit board substrate; and a return current strip that islongitudinally aligned adjacent to the pair of differential contactstrips and connected to a ground plane of the circuit board substrate,the converging narrowing of the adjacent differential contact stripincreasing separation from a distal end of the return current strip, theseparation improving signal integrity by reducing fringe effects,increasing impedance, and quenching resonance; a surface mount device(SMD) having one or more connector pins that correspond to and areattached to the one or more landing pads to conduct high-speedcommunication signals; and a processor subsystem.
 8. The IHS of claim 7,wherein the converging narrowing of each strip comprises a tapered end.9. The IHS of claim 7, wherein the converging narrowing of each stripcomprises a rounded end.
 10. The IHS of claim 7, wherein a longitudinallength of a converging narrowing portion of each strip of the pair ofdifferential contact strips is within a range of 30-50% of a totallongitudinal length of the respective landing pad.
 11. The IHS of claim1, further comprising a next return current strip that is longitudinallyaligned adjacent to the pair of differential contact strips, the nextreturn current strip connected to the ground plane of the circuit boardsubstrate, the return current strip and next return current stripextending on lateral sides of the pair of differential contact stripsthat are electrically connected as positive and negative values to ahigh communication speed functional component of the IHS.
 12. The IHS ofclaim 11, wherein the SMT landing pad is form by: attaching a metalliclayer onto a surface of the circuit board substrate; etching themetallic layer to leave the adjacent pair of differential contactstrips; attaching a return current strip; and attaching a raisedrectangular ridge around the adjacent pair of differential contactstrips to form the landing pad to guide the SMT connector pin of theSMD.
 13. A method comprising: attaching an adjacent pair of differentialcontact strips to a nonconductive surface of respective landing pads ofa surface mount technology (SMT) pad structure of a circuit boardsubstrate, the pair of differential contact strips having convergingnarrowing at a respective distal end and each having a proximal signaltrace for conducting a high-speed communication signal to anotherfunctional component attached to a circuit board substrate; andattaching a return current strip that is longitudinally aligned adjacentto the pair of differential contact strips on a first lateral side andconnected to a ground plane of the circuit board substrate, theconverging narrowing of the adjacent differential contact stripincreasing separation from a distal end of the return current strip, theseparation improving signal integrity by reducing fringe effects,increasing impedance, and quenching resonance; and attaching a surfacemount device (SMD) having one or more connector pins that correspond toand are attached to the one or more landing pads to conduct thehigh-speed communication signal and forming a circuit board assembly ofan information handling system.
 14. The method of claim 13, wherein theconverging narrowing of each strip comprises a tapered end.
 15. Themethod of claim 13, wherein the converging narrowing of each stripcomprises a rounded end.
 16. The method of claim 13, wherein alongitudinal length of the converging narrowing portion of each strip ofthe pair of differential contact strips is within a range of 30-50% of atotal longitudinal length of the respective landing pad.
 17. The methodof claim 13, further comprising attaching a next return current stripthat is longitudinally aligned adjacent to the pair of differentialcontact strips on a second lateral side, the next return current stripconnected to the ground plane of the circuit board substrate.
 18. Themethod of claim 13, further comprising: attaching a metallic layer ontoa surface of the circuit board substrate; etching the metallic layer toleave the adjacent pair of differential contact strips and attaching areturn current strip; and attaching a raised rectangular ridge aroundthe adjacent pair of differential contact strips to form the landing padto guide the SMT connector pin of the SMD.